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Selected contribution: Peripheral chemoreflex function in high-altitude natives and patients with chronic mountain
Fabiola Léon-Velarde1, Alfredo Gamboa, Maria Rivera-Ch
1Departmento De Ciencias Biologicas y Fisiologicas/IIA, Universidad Peruana Cayetano Heredia, Lima 100, Peru.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 7, 2003
Summary
High-altitude natives and chronic mountain sickness patients exhibit reduced acute ventilatory responses to hypoxia. Peripheral chemoreflex function is altered in these populations compared to sea-level natives.
Area of Science:
- Physiology
- Altitude Medicine
- Respiratory Physiology
Background:
- Peripheral chemoreceptors are crucial for regulating ventilation during hypoxia.
- High-altitude (HA) natives and individuals with chronic mountain sickness (CMS) may exhibit altered responses to hypoxic conditions.
- Understanding these adaptations is vital for managing respiratory health at altitude.
Purpose of the Study:
- To investigate and compare peripheral chemoreflex function in high-altitude (HA) natives, patients with chronic mountain sickness (CMS), and sea-level (SL) natives.
- To assess the acute ventilatory responses to hypoxia (AHVR) across these distinct populations.
- To explore the relationship between hematocrit and ventilatory responses in HA and CMS subjects.
Main Methods:
- Studied peripheral chemoreflex function in three groups: HA natives at HA, CMS patients at HA, and SL natives at SL.
- Measured acute ventilatory responses to hypoxia (AHVR) and hyperoxia.
- Administered dopamine and somatostatin to assess their effects on ventilation.
- Correlated end-tidal PCO2 and hematocrit with AHVR.
Main Results:
- HA and CMS groups showed approximately one-third the AHVR of the SL group.
- CMS patients had slightly lower AHVR indexes than healthy HA natives.
- Ventilatory response to hyperoxia was biphasic in all groups.
- Peripheral chemoreflex stimulation of ventilation was greater in HA and CMS subjects at lower end-tidal PO2.
- A strong correlation between end-tidal PCO2 and hematocrit was observed in HA and CMS subjects.
Conclusions:
- Peripheral chemoreflex sensitivity is diminished in high-altitude natives and CMS patients compared to sea-level natives.
- Chronic mountain sickness is associated with further, albeit modest, reductions in ventilatory responsiveness to hypoxia.
- Hematocrit levels are significantly correlated with ventilatory control in high-altitude populations, independent of AHVR.